Bosch Rexroth IndraDrive MPH-02 Functional Description page 225

MPH-02, MPB-02, MPD-02
Base Speed Range (1)
Field Weakening Range (2)
(Constant Power)
Field Weakening Range (3)
(Power Limit Range)
DOK-INDRV*-MP*-02VRS**-FK01-EN-P
P
P
max
P
S1
1 2
n1
Fig. 6-12: Working ranges
The base speed range is characterized by constant torque and fixed
torque/force constant (P-0-0051).
In the case of asynchronous motors, the programmed, effective
magnetizing current flows in no-load operation. The motor voltage is less
than the maximum controller output voltage. The corner speed n1 is
directly proportional to the DC bus voltage.
This field weakening range is characterized by constant power, the motor
voltage is kept constant. In the case of asynchronous motors, the no-load
current is reduced as the speed increases. This reduces the
magnetization and the torque constant, the slip increases accordingly.
The adjustment of magnetizing current and slip is automatically carried
out by the voltage loop.
The field weakening range is the range of decreasing peak power. An
asynchronous motor works at the stall current limit in this range, through
vector control, the current is maintained at an efficient and stable level.
The peak current is reduced in such a way that the point of maximum
power is not exceeded. Further increase in current would only lead to
increased power dissipation and less shaft output. The peak power in
range 3 is proportional to the square of the DC bus voltage. It is ensured
that the maximum possible power is reached for each DC bus voltage
without parameter adjustment.
Note: Due to this causal connection, it is clear that the power in
range 3 cannot be increased by using a more powerful
controller.
Field-Oriented Closed-Loop Current Control of a
Synchronous Machine
Synchronous motors with a motor encoder in field-oriented closed-loop
current control can be operated in all available operating modes. The
figure below illustrates the control loop structure and the points at which
the individual parameters take effect.
3
n2
Sv5025f 1.fh7
6-13
Drive Control
n